Threat Encyclopedia

TSPY_ZBOT.BX

Publish date: October 08, 2012

ANALYSIS BY

MarfelTi


PLATFORM:

Windows 2000, XP, Server 2003

OVERALL RISK RATING:
REPORTED INFECTION:
SYSTEM IMPACT RATING:
INFORMATION EXPOSURE:

  • Threat Type:Trojan

  • Destructiveness:No

  • Encrypted: No

  • In the wild: Yes

OVERVIEW


This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It attempts to steal sensitive online banking information, such as user names and passwords. This routine risks the exposure of the user's account information, which may then lead to the unauthorized use of the stolen data. Once users access any of the monitored sites, it starts logging keystrokes. It attempts to steal information, such as user names and passwords, used when logging into certain banking or finance-related websites.

It attempts to get information from a list of banks or financial institutions.

TECHNICAL DETAILS

File Size:

229,376 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

07 Apr 2011

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Infection Points

This Trojan arrives as a file downloaded from the following URLs:

  • http://{BLOCKED}lo-sar.com/ost.exe

Installation

This Trojan drops the following files:

  • {malware path}\Setup.dll

It drops copies of itself in the Windows system folder and appends garbage code to the dropped copy to avoid easy detection. The dropped copies uses the following file names:

  • %System\sdra64.exe

It then creates the following non-malicious file(s):

  • %System%\lowsec\local.ds - copy of the encrypted downloaded file
  • %System%\lowsec\user.ds - used to save the gathered information

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It creates the following folders with attributes set to System and Hidden to prevent users from discovering and removing its components:

  • %System%\lowsec

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • _AVIRA_2108

It injects itself into the following processes as part of its memory residency routine:

  • legitimate WINLOGON.EXE and SVCHOST.EXE

Autostart Technique

This Trojan modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = %System%\userinit.exe; %System\sdra64.exe;

(Note: The default value data of the said registry entry is %System%\userinit.exe;.)

Other System Modifications

This Trojan also creates the following registry entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Network
UID = {computer name}_{random numbers}

Information Theft

This Trojan attempts to steal sensitive online banking information, such as user names and passwords. This routine risks the exposure of the user's account information, which may then lead to the unauthorized use of the stolen data.

It accesses the following site to download its configuration file:

  • http://{BLOCKED}lo-sar.com/baki.bin

Once users access any of the monitored sites, it starts logging keystrokes.

It attempts to access a website to download a file which contains information where the Trojan can download an updated copy of itself, and where to send its stolen data. This configuration file also contains the following list of targeted bank-related websites from which it steals information:

  • https://www.bankofamerica.com/

The downloaded file contains information where the malware can download an updated copy of itself, and where to send its stolen data.

Note that the contents of the file, hence the list of websites to monitor, may change any time.

Note that the list may change anytime.

It attempts to steal information from the following banks and/or other financial institutions:

  • Bank of America

Attacked Entities

This Trojan attempts to get information from a list of banks or financial institutions.

Drop Points

The said file is then sent to the following URL via HTTP POST:

  • http://{BLOCKED}lo-sar.com/gate.php

Other Details

This Trojan attempts to access the following websites to download files, which are possibly malicious:

  • http://{BLOCKED}lo-sar.com/baki.bin

It did not exhibit backdoor routines during testing.

SOLUTION

Minimum Scan Engine:

8.900

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identifying the Spyware Files

  1. Scan your computer with your Trend Micro Anti-Spyware product.
  2. Note the path and file name of all files detected as TSPY_ZBOT.BX.

Trend Micro Anti-Spyware customers need to download the latest anti-spyware pattern file before scanning their computer. Other users can use Housecall, the Trend Micro online threat scanner.

Step 3

Identify and delete files detected as TSPY_ZBOT.BX using the Recovery Console

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.


  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Userinit = %System%\userinit.exe; %System\sdra64.exe;
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Network
    • UID = {computer name}_{random numbers}

Step 5

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
{malware path}\Setup.dll
%System\sdra64.exe
%System%\lowsec

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.BX. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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